Business Segments 1 - Group Reporting Basis to US GAAP Adjustments from previous table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net Interest Income	$ 2,303	$ 2,559	$ 2,387
Other Revenues	1,537	1,604	1,727
Provision for Credit Losses	171	(199)	(119)
Operating Expenses	3,313	3,633	3,333
Profit (Loss) before Income Tax Expense	356	729	900
Total Assets	214,223	203,375	220,313
Debt Extinguishment [Member]
Segment Reporting Information [Line Items]
Net Interest Income	0
Other Revenues	123
Provision for Credit Losses	0
Operating Expenses	0
Profit (Loss) before Income Tax Expense	123
Total Assets	0
Deposit Incentives [Member]
Segment Reporting Information [Line Items]
Net Interest Income	15	9
Other Revenues	0	0
Provision for Credit Losses	0	0
Operating Expenses	32	20
Profit (Loss) before Income Tax Expense	(17)	(11)
Total Assets	(23)	(10)
Derivatives [Member]
Segment Reporting Information [Line Items]
Net Interest Income	0	0	0
Other Revenues	0	0	0
Provision for Credit Losses	0	0	0
Operating Expenses	0	0	0
Profit (Loss) before Income Tax Expense	0	0	0
Total Assets	(38,651)	(30,866)	(32,900)
Expected Credit Losses/Loan Impairment [Member]
Segment Reporting Information [Line Items]
Net Interest Income	(3)	(6)	(43)
Other Revenues	(1)	0	0
Provision for Credit Losses	32	118	(72)
Operating Expenses	0	0	0
Profit (Loss) before Income Tax Expense	(36)	(124)	29
Total Assets	(357)	(386)	(332)
Goodwill [Member]
Segment Reporting Information [Line Items]
Net Interest Income	0	0	0
Other Revenues	0	0	(1)
Provision for Credit Losses	0	0	0
Operating Expenses	156	0	0
Profit (Loss) before Income Tax Expense	(156)	0	(1)
Total Assets	191	347	347
Leases [Member]
Segment Reporting Information [Line Items]
Net Interest Income	25
Other Revenues	0
Provision for Credit Losses	0
Operating Expenses	8
Profit (Loss) before Income Tax Expense	17
Total Assets	15
Loan Origination [Member]
Segment Reporting Information [Line Items]
Net Interest Income	(27)	(29)	(19)
Other Revenues	0	(3)	0
Provision for Credit Losses	0	0	0
Operating Expenses	(19)	(14)	(14)
Profit (Loss) before Income Tax Expense	(8)	(18)	(5)
Total Assets	38	45	42
Loans Held for Sale [Member]
Segment Reporting Information [Line Items]
Net Interest Income	2	9	9
Other Revenues	(1)	6	141
Provision for Credit Losses	0	(3)	0
Operating Expenses	0	0	0
Profit (Loss) before Income Tax Expense	1	18	150
Total Assets	(5)	45	21
Pension and Other Postretirement Benefit Costs [Member]
Segment Reporting Information [Line Items]
Net Interest Income	0	0	0
Other Revenues	0	0	0
Provision for Credit Losses	0	0	0
Operating Expenses	(12)	8	94
Profit (Loss) before Income Tax Expense	12	(8)	(94)
Total Assets	0	(44)	(263)
Property [Member]
Segment Reporting Information [Line Items]
Net Interest Income		0	0
Other Revenues		0	0
Provision for Credit Losses		0	0
Operating Expenses		(8)	(11)
Profit (Loss) before Income Tax Expense		8	11
Total Assets		7	8
Renewable Energy Tax Credit Investments [Member]
Segment Reporting Information [Line Items]
Net Interest Income	0	0	(4)
Other Revenues	(7)	(10)	(7)
Provision for Credit Losses	0	0	0
Operating Expenses	0	0	0
Profit (Loss) before Income Tax Expense	(7)	(10)	(11)
Total Assets	3	3	9
Securities Transferred to Held-to-maturity [Member]
Segment Reporting Information [Line Items]
Net Interest Income	0	0
Other Revenues	0	0
Provision for Credit Losses	0	0
Operating Expenses	0	0
Profit (Loss) before Income Tax Expense	0	0
Total Assets	(65)	(76)
Structured Notes and Deposits [Member]
Segment Reporting Information [Line Items]
Net Interest Income			0
Other Revenues			85
Provision for Credit Losses			0
Operating Expenses			0
Profit (Loss) before Income Tax Expense			85
Total Assets			0
Other [Member]
Segment Reporting Information [Line Items]
Net Interest Income	1	1	9
Other Revenues	(12)	(2)	(18)
Provision for Credit Losses	0	0	0
Operating Expenses	4	(3)	6
Profit (Loss) before Income Tax Expense	(15)	2	(15)
Total Assets	6	8	(10)
Total Adjustments [Member]
Segment Reporting Information [Line Items]
Net Interest Income	13	(16)	(48)
Other Revenues	102	(9)	200
Provision for Credit Losses	32	115	(72)
Operating Expenses	169	3	75
Profit (Loss) before Income Tax Expense	(86)	(143)	149
Total Assets	$ (38,848)	$ (30,927)	$ (33,078)